Today's internal combustion engines must meet ever-stricter emissions and efficiency standards demanded by consumers and government regulatory agencies. Accordingly, automotive manufacturers and suppliers expend great effort and capital in researching and developing technology to improve the operation of the internal combustion engine. Turbochargers are one area of engine development that is of particular interest.
A turbocharger uses exhaust gas energy, which would normally be wasted, to drive a turbine. The turbine is mounted to a shaft that in turn drives a compressor. The turbine converts the heat and kinetic energy of the exhaust into rotational power that drives the compressor. The objective of a turbocharger is to improve the engine's volumetric efficiency by increasing the density of the air entering the engine. The compressor draws in ambient air and compresses it into the intake manifold and ultimately the cylinders. Thus, a greater mass of air enters the cylinders on each intake stroke.
Given that a turbocharger must handle exhaust straight from the engine, it can be appreciated that the components of a turbocharger are subjected to extreme temperatures. Because the turbocharger is mounted to the engine, the turbocharger and its ancillary components are also subject to vibration. In addition to temperature, engine vibration contributes to wear among the various ancillary components including the variable turbine geometry (VTG) linkages.
In particular, the VTG linkages include rod ends that have a tendency to wear out. The rod ends wear due to two types of wear: pressure/velocity and vibration impact. During the initial life of the assembly, wear is limited to pressure/velocity and is relatively slow and linear. However, as clearance is worn between the ball and race, vibration impact wear becomes predominant. The vibration impact wear rate is much steeper and quickly leads to component failure. Accordingly, there is a need for a self adjusting rod end that compensates for clearance worn between the ball and race.